NavList:

Pär Leijonhufvud you wrote:  But in a survival situation you often only need a "close enought" direction. 

Pär
I agree.  I can think of situations where a rough guide to south would be of value.  When sleep deprived and exhausted and beginning to question one’s sanity, let alone one’s compass; a subliminal jab when things might be going wrong e.g. an unnoticed runaway variation setting control; to save frequent viewing of, or frequently shining a torch on the compass.  There must be many more occasions. 
The important thing is to stress that the direction indicated on the observer’s horizon will usually be approximate and to give some information how far from true south the direction indicated by the ‘pointer’ might be.  Checking how far off tonight, also gives you another little pastime, like pacing, to occupy bored students on night exercises. In fact, on Saturday 12th Feb evening at about 20.00LMT from 53.159491 -0.540500, I was only checking casually whilst getting my daily four miles in, but if you'd have looked at a negative photograph of the Moon, i.e. cream is black and black is cream , the line wouldnt have been far off true south on my horizon. DaveP